Skip to main content



Information Cascades in Swarms

In 2012, five affiliates of CSIRO Information and Communication Technologies Centre in Australia took on the task of finding what social interactions are in play when a swarm of animals moves a certain direction. They observed that the spatial position of an individual in a group of animals such as a school of fish or a flock of birds plays a huge role in the decision making process for that individual. That is to say that where an individual in a swarm decides to move is highly influenced by what position they are in the swarm. They hypothesized that since an individual in a swarm can only see and be influenced by other individuals directly next to themselves, the direction a swarm moves is due to an information cascade amongst individuals in the swarm.

Using computational analysis, the group of researchers were able to take real world observations as well as mathematical models to explore how much of a presence information cascades have on swarms. Their results found that individuals in the center of a swarm are not affected much by the individuals around them while the individuals on the edge of the swarm are greatly influenced by their neighbors. This is almost as if the individual at the middle of the swarm is doing all of the steering. With respect to a school of fish, this would mean that the fish in the middle of the school are doing all of the steering. This may seem a little fishy since the fish at the middle of the school won’t be able to see where to go.

The researchers understood this blind driver predicament and with further analysis found that there is another element influencing the direction of motion of a swarm. This element is AIS which stands for Active Information Storage and is the average information received per individual in a period of time. With respect to networks, if individuals in a group receive either high or low signals, the AIS corresponds to the average signal received by the group. The group will subsequently act according to this average. The researchers found that once a swarm is moving in tandem, the swarm’s motion is then greatly influenced by AIS. Since the boundary layer of a swarm is also the largest layer of a swarm, there is a good chance that the average signal the boundary layer receives is the ultimate deciding factor for where the swarm moves.

In summary, the motion of a swarm prior to a swarm moving in unison is greatly influenced by an information cascade that leads individuals to move towards the middle of a swarm. After the individuals in a swarm are moving in unison, the movement of a swarm is mostly influenced by the boundary layer of a swarm.

Article:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0040084

 

The videos below help you visualize the influence that information cascades have on swarm formation.

They also show why schools of fish look like this

Comments

Leave a Reply

Blogging Calendar

November 2014
M T W T F S S
 12
3456789
10111213141516
17181920212223
24252627282930

Archives